Process for producing diesel

Abstract

A process is disclosed for hydrocracking a primary hydrocarbon feed and a diesel co-feed in a hydrocracking unit and hydrotreating a diesel product from the hydrocracking unit in a hydrotreating unit. The diesel stream fed through the hydrocracking unit is pretreated to reduce sulfur and ammonia and can be upgraded with noble metal catalyst.

The invention claimed is: 
     
       1. A process for producing diesel from a hydrocarbon stream comprising:
 hydrotreating a primary hydrocarbon stream and a co-feed hydrocarbon stream comprising diesel in the presence of a hydrogen stream and pretreating catalyst to provide a pretreated effluent stream; 
 hydrocracking the pretreated effluent stream in the presence of hydrocracking catalyst and hydrogen to provide a hydrocracking effluent stream; 
 fractionating at least a portion of the hydrocracking effluent stream to provide a diesel stream; 
 hydrotreating the diesel stream in the presence of a hydrotreating hydrogen stream and hydrotreating catalyst to provide a hydrotreating effluent stream; 
 separating the hydrocracking effluent stream into a vaporous hydrocracking effluent stream comprising hydrogen and a liquid hydrocracking effluent stream; 
 compressing the vaporous hydrocracking effluent stream with a compressed make-up hydrogen stream to provide a compressed hydrogen stream; and 
 taking the hydrotreating hydrogen stream from the compressed hydrogen stream. 
 
     
     
       2. The process of  claim 1  wherein the hydrotreating catalyst comprises a noble metal catalyst. 
     
     
       3. The process of  claim 1  wherein the hydrotreating catalyst comprises a desulfurization catalyst. 
     
     
       4. The process of  claim 1  wherein the hydrotreating catalyst comprises an isomerization catalyst. 
     
     
       5. The process of  claim 1  wherein the hydrotreating catalyst comprises an aromatic saturation catalyst. 
     
     
       6. The process of  claim 1  further comprising fractionating the liquid hydrocracking effluent stream to remove hydrogen sulfide and ammonia and provide the diesel stream. 
     
     
       7. The process of  claim 1  wherein the primary hydrocarbon feed stream has an initial boiling point no less than about 150° C. (302° F.) and an end point of no more than about 621° C. (1150° F.). 
     
     
       8. The process of  claim 1  wherein the co-feed stream has an initial boiling point between about 121° C. (250° F.) and about 288° C. (550° F.). 
     
     
       9. The process of  claim 8  wherein the co-feed has an end point of no more than about 399° C. (750° F.). 
     
     
       10. The process of  claim 1  wherein the diesel stream has an initial boiling point between about 121° C. (250° F.) and about 288° C. (550° F.). 
     
     
       11. The process of  claim 1  wherein the diesel stream has an end point of no more than about 399° C. (750° F.). 
     
     
       12. The process of  claim 11  wherein the diesel stream has a sulfur concentration of no more than 150 wppm. 
     
     
       13. The process of  claim 1  further comprising separating the hydrotreating effluent stream into a vaporous hydrotreating effluent stream comprising hydrogen and a liquid hydrotreating effluent stream and mixing the vaporous hydrotreating effluent stream comprising hydrogen with the hydrocracking effluent stream. 
     
     
       14. The process of  claim 1  further comprising separating the hydrotreating effluent stream into a vaporous hydrotreating effluent stream comprising hydrogen and a liquid hydrotreating effluent stream and fractionating the liquid hydrotreating effluent stream comprising at least 90 wt-% diesel to provide an ultra low sulfur diesel stream. 
     
     
       15. A process for producing diesel from a hydrocarbon stream comprising:
 feeding a primary hydrocarbon stream to a pretreat hydrotreating reactor; 
 co-feeding a co-feed hydrocarbon stream having an initial boiling point between about 121° C. (250° F.) and about 288° C. (550° F.) to said pretreat hydrotreating reactor; 
 hydrotreating said primary hydrocarbon stream and said co-feed hydrocarbon stream in the presence of a hydrogen stream and pretreating catalyst to provide a pretreated effluent stream; 
 hydrocracking the pretreated effluent stream in the presence of hydrocracking catalyst and the hydrocracking hydrogen stream remaining in the pretreated effluent stream to provide a hydrocracking effluent stream; 
 fractionating at least a portion of the hydrocracking effluent stream to provide a diesel stream having an initial boiling point between about 121° C. (250° F.) and about 288° C. (550° F.); 
 hydrotreating the diesel stream in the presence of a hydrotreating hydrogen stream and hydrotreating catalyst to provide a hydrotreating effluent stream; 
 separating the hydrocracking effluent stream into a vaporous hydrocracking effluent stream comprising hydrogen and a liquid hydrocracking effluent stream; 
 compressing the vaporous hydrocracking effluent stream with a compressed make-up hydrogen stream to provide a compressed hydrogen stream; and 
 taking the hydrotreating hydrogen stream from the compressed hydrogen stream. 
 
     
     
       16. The process of  claim 15  wherein the co-feed stream and the diesel stream both have an end point of no more than about 399° C. (750° F.). 
     
     
       17. The process of  claim 15  wherein the hydrotreating catalyst comprises a noble metal catalyst. 
     
     
       18. A process for producing diesel from a hydrocarbon stream comprising:
 feeding a primary hydrocarbon stream having an initial boiling point of no less than about 150° C. (302° F.) and an end point of no more than about (565° C.) 1050° F. to a pretreat hydrotreating reactor; 
 co-feeding a co-feed hydrocarbon stream having an initial boiling point between about 121° C. (250° F.) and about 288° C. (550° F.) to said pretreat hydrotreating reactor; 
 hydrotreating the primary hydrocarbon stream and the co-feed hydrocarbon stream in the presence of the hydrocracking hydrogen stream and pretreating catalyst to provide a pretreated effluent stream; 
 hydrocracking the pretreated effluent stream in the presence of hydrocracking catalyst the hydrocracking hydrogen stream remaining in the pretreated effluent stream to provide a hydrocracking effluent stream; 
 fractionating at least a portion of the hydrocracking effluent stream to provide a diesel stream having an initial boiling point between about 121° C. (250° F.) and about 288° C. (550° F.); 
 hydrotreating the diesel stream in the presence of a hydrotreating hydrogen stream and hydrotreating catalyst to provide a hydrotreating effluent stream; 
 separating the hydrocracking effluent stream into a vaporous hydrocracking effluent stream comprising hydrogen and a liquid hydrocracking effluent stream; 
 compressing the vaporous hydrocracking effluent stream with a compressed make-up hydrogen stream to provide a compressed hydrogen stream; and 
 taking the hydrotreating hydrogen stream from the compressed hydrogen stream. 
 
     
     
       19. The process of  claim 18  wherein the co-feed stream and the diesel stream both have an end point of no more than about 399° C. (750° F.).